1. Field of the Invention
The present invention relates to a mainspring device, a timepiece, and a method of controlling the mainspring device and the timepiece. The present invention can be applied to a mechanical timepiece including a mainspring, which is wound up either by hand or automatically, and a timed annular balance, and to an electronic control type mechanical timepiece in which hands, affixed to a wheel train, are moved precisely by converting mechanical energy, output when the mainspring is unwound, into electrical energy by a generator in order to actuate a rotation controller using the electrical energy and control the rotation period of the generator.
2. Description of the Related Art
A mechanical timepiece whose hands are moved by utilizing mechanical energy of a mainspring is conventionally known.
Many electronic control type mechanical timepieces, such as that disclosed in Japanese Unexamined Patent Publication No. 8-5758, have been used in recent years. The timepiece, disclosed in the aforementioned document, indicates the exact time by precisely moving the hands affixed to a wheel train. The hands are moved by converting mechanical energy, output when the mainspring is unwound, into electrical energy by a generator in order to actuate a rotation controller using the electrical energy and to control the value of the current flowing in the coil of the generator.
As shown in FIG. 22, at the stage of winding up a mainspring when the number of windings reaches a predetermined number A, the torque that has been accumulating in the mainspring suddenly becomes large so that a very large torque is output when unwinding of the mainspring is started. The large torque is exerted onto a controlling portion of a speed regulator or an escapement, for example, which controls the rotational speed of a wheel train which rotates the mainspring. This sudden, large torque may cause component parts of the timepiece to break.
On the other hand, at the last stage of unwinding a mainspring when the number of windings is equal to or less than a predetermined number B, the torque output from the mainspring becomes very small, causing the hands to gradually slow down. This may cause the timepiece to indicate the wrong time. In an electronic control type mechanical timepiece, for example, when the mainspring is unwound to a certain degree, the amount of electrical power generated by the generator becomes so small that the generator rotates at a speed which is less than a speed that can be controlled. Therefore, the hands do not move precisely, causing the timepiece to indicate the wrong time.
To prevent this circumstance, clocks are provided with a winding-up and unwinding stop mechanism that prevents winding or unwinding of the mainspring beyond a certain maximum number of windings (during winding) or minimum number of windings (during unwinding). In general, the winding-up and unwinding stop mechanism uses a maltese-cross type mechanism, such as that shown in FIG. 23. It includes a finger 102, affixed to a barrel arbor 101, and a gear 103, called a maltese-cross, mounted to a barrel drum.
As shown in FIG. 23(A), a finger head 102a of the finger 102 engages a cut in the gear 103, which can rotate freely, initially, and move along the circumference of the finger 102 by progressively sliding therealong.
When the timepiece is wound, the barrel arbor 101 rotates, causing the finger 102 to rotate, so that one tooth of the gear 103 advances upon one rotation. Eventually, as shown in FIG. 23 (A), a flat tooth 103a of the gear 103 engages the finger head 102a, thereby stopping the rotation of the barrel arbor 101 and locking the winding-up operation to prevent further winding of the mainspring.
During operation of the timepiece (that is, when the mainspring is being unwound), the finger 102 is fixed, and the gear 103 rotates along with the barrel drum, with the barrel arbor 101 at the center, such that one tooth advances upon one rotation, as shown in FIG. 23(B). After the barrel drum rotates four times, the flat tooth 103a and the finger head 102a engage each other, as shown in FIG. 23(C), thereby locking the unwinding operation to prevent any further unwinding of the mainspring.
The maltese-cross type winding-up and unwinding stop mechanism has a simple structure and requires few parts. However, since the winding operation is stopped by bringing a flat tooth of a gear into contact with a finger head, both components must be strong, which is realized by making them relatively large.
In addition, the finger and the gear must be placed upon a barrel drum. This causes the barrel drum to become thicker, so that the above-described maltese-cross winding-up and unwinding stop mechanism can only be used in a clock which has a large space for accommodating component parts in its interior, and cannot be used in watches which only have a small space available for components.
Therefore, in watches, it is difficult to limit the winding up and unwinding of the mainspring. As a result, breakage of parts still occurs when a very large torque is exerted onto the parts, and the wrong time is indicated when the torque becomes very small. Consequently, there is a demand for a way to output a torque whose value lies within a set range during winding and unwinding.
Accordingly, it is an object of the present invention to provide a mainspring device, a timepiece, and a method of controlling the mainspring device and the timepiece, wherein even when the mainspring device is used in a watch having a small space for accommodating component parts in its interior, neither an excessive torque nor an inadequate torque is output, that is, a torque that is within a set range is output at all times.
Electronic control type mechanical timepieces can control with high precision the rotation period of a generator, that is, the rotational period of the hands. This precision control results from driving a rotation control circuit, which includes a crystal oscillator, using electrical energy that has been generated in the timepiece. Such timepieces can indicate time more accurately than a conventional mechanical timepiece.
However, since it is necessary to stop the hands during hand adjustments, the wheel train, as well as the generator, must be stopped. Therefore, when the generator is stopped so that generation of electrical power is stopped, driving of the rotation control circuit can be continued only for a certain period of time using the electrical power stored in a charged capacitor. However, when the capacitor has completely discharged, the rotation control circuit stops.
After the rotation control circuit has stopped, when hand adjustments are completed and driving of the generator is started, hand movements cannot be controlled until driving of the control circuit is started. Therefore, there has been an attempt to preset the time during which hand movements cannot be controlled in order to correct the starting time of the control operation. Here, when the magnitude of the torque output from the mainspring changes, the amount of time until which the generator drives the control circuit also changes, so that the amount of correction is set in accordance with the magnitude of a predetermined output torque.
However, at the last stage of mainspring winding-up operations the torque accumulated in the mainspring suddenly becomes large, and a slight change in the winding amount greatly changes the magnitude of the torque, causing the torque to change greatly with every winding operation. Therefore, the corrections, even when they are made, are not sufficient.
It is another object of the present invention to provide a mainspring device, a timepiece, and a method of controlling the mainspring device and the timepiece, wherein when, for example, an electronic control type mechanical timepiece is used, corrections can be made very precisely even when the rotation control circuit has been stopped.
According to the present invention, there is provided a mainspring device constructed so as to drive a wheel train by mechanical energy of a mainspring, comprising: a winding-up portion for accumulating energy in the mainspring; an addition and subtraction wheel train for adding and subtracting the amount by which the mainspring is wound up and unwound; an addition and subtraction wheel, disposed in the addition and subtraction wheel train, for adding and subtracting the amount by which the mainspring is wound up and unwound; and a lock mechanism, which is actuated in response to the rotation of the addition and subtraction wheel, for preventing transmission of torque with a value that lies outside a set range from the mainspring to the wheel train.
According to the present invention, the amount by which the mainspring is wound up and unwound is detected by using an addition and subtraction wheel train, and the lock mechanism is actuated in response to the rotation of the addition and subtraction wheel to which a torque produced during the winding or unwinding operation is exerted. Therefore, the winding operation can be locked before the torque on the mainspring becomes very large, or the wheel train can be stopped before rotation of the wheel train becomes imprecise as a result of a reduction in the output torque. Therefore, a torque whose value lies within a set range can be output at all times.
The addition and subtraction wheel train is constructed using a plurality of gears or the like, making it unnecessary to construct it like the maltese-cross type winding stop mechanism, which is constructed using only two members that are directly mounted to the barrel arbor and the movement barrel. Therefore, the addition and subtraction wheel, or the like, can be disposed in the space around the movement barrel through the wheel train. Consequently, even when the mainspring device is used in a watch having only a small space for accommodating component parts, the addition and subtraction wheel train can be disposed in ample space, making it possible to stop the winding up of the mainspring.
For example, the lock mechanism may comprise a winding-up lock mechanism portion which, when the mainspring is wound up to a predetermined value, locks a winding-up wheel train in order to stop the winding up of the mainspring. Torque produced during winding-up operations is transmitted to the winding-up wheel train disposed in the addition and subtraction wheel train, and/or the winding-up portion.
In this form, when the mainspring is wound up to a number of windings that is equal to or greater than a predetermined value, the winding-up wheel train and the winding-up portion are locked (stopped) by the winding-up lock mechanism portion in response to the rotation of the addition and subtraction wheel. Thus, the winding-up operation can be more reliably stopped, thus making it possible to prevent, in particular, overwinding of the mainspring.
Here, the winding-up lock mechanism portion is not required to perform locking operations by disengaging a gear. For example, the winding-up lock mechanism portion may stop the winding up of the mainspring by locking a torque transmitting component part which has a torque equal to or less than a gear directly connected to a torque input side of the mainspring and which is disposed in the winding-up wheel train and/or the winding-up portion.
Locking a torque transmitting part (for example, a gear) with a smaller torque allows the winding-up operation to be stopped with a smaller force. Therefore, the strength of the component parts of the winding-up lock mechanism portion can be made small, which allows the parts to be made smaller and thinner.
For example, the winding-up lock mechanism portion may perform a locking operation by stopping torque transmission to the winding-up wheel train or to the winding-up portion.
Further, the lock mechanism may be, for example, an unwinding lock mechanism portion which, when the mainspring is unwound to a number of windings, equal to or less than a predetermined value, stops the rotation of the wheel train by locking a unwinding wheel train. Torque produced during unwinding operations is transmitted to the unwinding wheel train disposed in the addition and subtraction wheel train, and/or the wheel train.
In this form, the unwinding lock mechanism portion, which operates in response to the rotation of the addition and subtraction wheel, locks the wheel train when the mainspring is unwound to a number of windings equal to or less than the predetermined value, so that the wheel train can be forced to stop before it becomes incapable of rotating precisely as a result of reduced output torque in the mainspring.
The unwinding lock mechanism portion may, for example, stop hand movement by disengagement of a gear in the wheel train. A gear can be disengaged by a lever, for example, which is actuated in response to the number of windings of the mainspring reaching a predetermined value. This prevents the torque on the mainspring from being transmitted, thereby allowing the wheel train to be reliably stopped.
The unwinding lock mechanism portion is not required to perform a locking operation by disengaging gears. It may, for example, stop the rotation of the wheel train by locking a torque transmitting component part which has a torque equal to or less than a gear directly connected to a torque output side of the mainspring and which is disposed in the unwinding wheel train and/or the wheel train.
By locking a gear with a small torque, the unwinding operation can be stopped with less force than that required to stop hand movements in the case where the torque on the movement barrel is directly received to stop the unwinding operation. Therefore, the required strength of the component parts of the unwinding lock mechanism is reduced, which allows these component parts to be made small and thinner.
It is also desirable that the winding-up lock mechanism portion lock a gear in the winding-up wheel train with any gear in a torque transmission path formed on the mainspring side, with reference to the gear being driven by rotation of an oscillating weight in order to cause the torque from the oscillating weight to wind up the mainspring and to drive the winding-up wheel train. The winding-up lock mechanism portion comprises a slip mechanism section, which is provided in the torque transmission path, for preventing transmission of torque, during actuation of the winding-up lock mechanism, from the oscillating weight to the mainspring and the addition and subtraction wheel.
In this case, when a gear is locked by the winding-up lock mechanism portion, a slip mechanism portion is actuated to cause the oscillating weight to rotate idly, so that when the oscillating weight is locked the oscillating weight itself is not broken, and rotation is not transmitted from the oscillating weight towards the addition and subtraction wheel, thereby preventing breakage of the winding-up lock mechanism portion in a locked state due to undue force exerted thereon, and ensuring that the hand of the addition and subtraction wheel indicates the exact time. Therefore, the winding-up lock mechanism portion can be applied to an automatic winding type mainspring device.
It is preferable that the winding-up lock mechanism portion comprise a winding-up lock lever which is lockable by engagement with at least one of the component parts to which torque is transmitted during a winding. up operation; and that the unwinding lock mechanism comprise an unwinding lock lever which is lockable by engagement with at least one of the component parts to which torque is transmitted during an unwinding operation. These lock levers ensure proper locking operations.
It is preferable that the winding-up lock lever has a stopper portion which is engageable with at least one gear in the winding-up wheel train and/or the winding-up portion; and that the unwinding lock lever has a stopper portion which is engageable with at least one gear in the unwinding wheel train and/or the wheel train.
Although the winding-up wheel train, the winding-up portion, the unwinding wheel train, and the wheel train can be locked by braking the wheel trains that are torque transmitting component parts, by, for example, frictional force, the winding-up wheel train and the winding-up portion can be reliably and easily locked by engaging the lever stopper portion with the teeth of a gear.
One wheel or a plurality of wheels may be brought into engagement with the stopper portion in order to perform a locking operation.
When the lock mechanism comprises the aforementioned winding-up lock mechanism portion and the unwinding lock mechanism portion, they may be integrally formed into one multilock lever in order to reduce the number of component parts and to allow more efficient use of space.
It is preferable that the rotational center of the winding-up lock lever, the unwinding lock lever, and the multilock lever be disposed between corresponding component parts with which the lock levers engage, and the corresponding addition and subtraction wheels. In this case, the distance from the rotational centers to the corresponding component parts and the distance from the rotational centers to the corresponding addition and subtraction wheels can be made shorter, so that each of the lock levers can be made more rigid.
It is desirable that the addition and subtraction wheel have an operation engaging portion, being a groove or a protrusion, at the outer periphery thereof; and the lock lever press-contact the addition and subtraction wheel, and have an engaging protrusion which is engageable with the operation engaging portion of the addition and subtraction wheel; and that when the engaging protrusion is brought into engagement with the operation engaging portion of the addition and subtraction wheel, the lock lever engages and stops the component part associated therewith.
When the engaging protrusion of the lock lever is made to press-contact the addition and subtraction wheel, the engaging protrusion can reliably be brought into engagement with the operation engaging portion, such as a groove, or can be kept in contact with the outer periphery of the addition and subtraction wheel, allowing the lock lever to be stable and actuated without any vibration, and thus making the winding-up lock mechanism portion and the unwinding lock mechanism portion more reliable.
It is preferable that the lock lever press and clamp the sides of the addition and subtraction wheel about its circumference. This helps to secure the rotational shaft of the addition and subtraction wheel in position.
Preferably, the portion of the lock lever that engages the associated component part may be made resilient. In this case, even when a force is further exerted onto the engaging portion of the lock lever in engagement with its associated component part, this exerted force is absorbed by the resilient engaging portion, so that undue force does not act on the component part, thereby preventing breakage thereof.
In another embodiment, the portion of the lock lever which engages the associated component part may be made rigid; and the addition and subtraction wheel, which actuates the lock lever, may be mounted on the same rotational shaft of a gear that transmits torque to the addition and subtraction wheel. Backlash is provided between the gear and the addition and subtraction wheel, the addition and subtraction wheel rotating ahead of the gear by an amount corresponding to the amount of backlash when the lock lever is being actuated.
In this case, the lock lever, which is rigid, can reliably perform a locking operation with a large amount of dragging force. Since, at the moment the lock lever engages its associated component part, the addition and subtraction wheel (or operation engaging portion) rotates ahead, the lock lever can be instantaneously brought into engagement with its associated component part, so that even when the lock lever is made rigid, less wear, or the like, occurs in the associated component part.
In the present invention, when the winding-up lock lever and the unwinding lock lever are separately formed, the term xe2x80x9cthe lock leverxe2x80x9d may refer to one of these lock levers or both of these lock levers, whereas when the winding-up lock lever and the unwinding lock lever are integrally formed to form one multilock lever, the term xe2x80x9cthe lock leverxe2x80x9d refers to the multilock lever.
It is preferable that the timepiece of the present invention comprise a remaining life indicator that is driven by the addition and subtraction wheel. In this case, the remaining life indicator allows the life of the timepiece to be easily read. Preferably, the remaining life indicator is provided at the outer side of a wheel train bridge, which supports the wheel train. Since the remaining life indicator is provided at the back side of the timepiece, the design at the front side can be kept simple, while providing a remaining life confirmation function.
It is preferable that the mainspring device be an electronic control type which comprises a generator for converting mechanical energy of the mainspring transmitted through the wheel train into electrical energy, and a rotation controller, which is driven by the electrical energy, for controlling the rotation period of the generator.
The mainspring device of the present invention may form part of a timepiece.
In the present invention, there is provided a timepiece which comprises a mainspring for accumulating therein energy by actuating a winding-up portion, a generator for converting mechanical energy of the mainspring transmitted through a wheel train into electrical energy, a hand connected to the wheel train, and a rotation controller, which is driven by the electrical energy, for controlling the rotation period of the generator. The timepiece further comprises either one of a winding-up lock mechanism which, when the mainspring is wound up to a number of windings that is equal to or greater than a predetermined number of windings, stops the winding up of the mainspring by locking the winding-up portion; and an unwinding lock mechanism which, when the mainspring is unwound to a number of windings that is equal to or less than a predetermined number of windings, stops hand movement by locking the wheel train that transmits torque from the mainspring towards the generator.
In such an electronic control type mechanical timepiece, when a winding-up lock mechanism is provided, the winding up of the mainspring can be locked when it is wound up to a predetermined number of windings, so that at the start of unwinding of the mainspring the output torque will not be very large, whereby the output torque can be kept at a virtually constant value. Upon startup of the rotor immediately after hand adjustments, it is possible to precisely predict when control operations can be performed after driving of the control circuit is started. Even when the rotation control circuit is not operating during hand adjustments performed after locking the winding-up operation, corrections can be made very precisely during the time the control circuit is not operating. Therefore, the electronic control type mechanical timepiece can indicate time even more precisely.
In such an electronic control type mechanical timepiece provided with a winding-up lock mechanism, even when, as described above, the output torque on the mainspring is reduced to a low value so that precise hand movements cannot be achieved, the wheel train and the hand can be forced to stop, thus allowing torque within a set range to be output at all times.
Preferably, the timepiece may further comprise a timepiece hand adjusting mechanism, and a hand-adjusting lock mechanism which, when the mainspring is unwound to the number of windings that is equal to or less than the predetermined number of windings, locks the timepiece hand adjusting mechanism so that it is not actuated.
When a hand adjusting lock mechanism is provided, hand adjustments cannot be performed until the mainspring is sufficiently wound up. Hand adjustments can then be performed after a capacitor has been charged. Therefore, when the timepiece is reset after hand adjustments, the system can be kept driven by the capacitor, thereby allowing hand movements to be controlled very precisely.
It is preferable that the electronic control type mechanical timepiece further comprise an addition and subtraction wheel train driven by the addition and subtraction of accumulated energy corresponding to the amount by which the mainspring is wound up and unwound, respectively. Also provided is an addition and subtraction wheel, disposed in the addition and subtraction wheel train, for transmitting thereto torque obtained by adding and subtracting the amount by which the mainspring is wound up and unwound, wherein the winding-up lock mechanism is actuated in response to the rotation of the addition and subtraction wheel when the mainspring is wound up to the number of windings that is equal to or greater than a first predetermined number of windings, and locks the winding-up wheel train, to which torque produced during a winding-up operation is transmitted in the addition and subtraction wheel train, and/or the winding-up portion, in order to stop the winding up of the mainspring.
By using an addition and subtraction wheel train, space can be efficiently used, and the winding up of the mainspring can be stopped even within the confines of a watch.
It is desirable that the electronic control type mechanical timepiece comprise the addition and subtraction wheel train driven by the addition and subtraction of accumulated energy corresponding to the amount by which the mainspring is wound up and unwound, respectively, and the addition and subtraction wheel, which is disposed in the addition and subtraction wheel train, for transmitting thereto torque obtained by adding and subtracting the amount by which the mainspring is wound up and unwound; wherein the unwinding lock mechanism portion which, when the mainspring is unwound to the number of windings that is equal to or less than a predetermined number of windings, is actuated in response to the rotation of the addition and subtraction wheel, and which locks the unwinding wheel train, to which torque produced during unwinding operations is transmitted in the addition and subtraction wheel train, and/or the wheel train connected to the unwinding wheel train, in order to stop hand movement.
By using an addition and subtraction wheel train, space can be efficiently used, and the unwinding of the mainspring can be stopped even in the confines of a watch.
The present invention also provides a method of controlling a winding-up operation of a mainspring device comprising a mainspring, a generator for converting mechanical energy of the mainspring transmitted through a wheel train into electrical energy, and a rotation controller, which is driven by the electrical energy produced by the generator, for controlling the rotation period of the generator, wherein when the mainspring is wound up to a number of windings that is equal to or greater than a predetermined number of windings, by a winding-up portion, used for accumulating energy in the mainspring, and the winding-up lock mechanism locks the winding-up portion in order to stop the winding up of the mainspring.
In the present invention, since the winding up of the mainspring can be locked when the mainspring is wound up to the predetermined number of windings, the output torque produced when unwinding of the mainspring is started is not very large, so that the output torque can be kept at a virtually constant value, whereby corrections can be made very precisely while the control circuit is not operating.
In the present invention, there is provided a method of controlling a winding-up operation of a mainspring device comprising a mainspring, a generator for converting mechanical energy of the mainspring transmitted through a wheel train to electrical energy, and a rotation controller, which is driven by the electrical energy produced by the generator, for controlling the rotation period of the generator, wherein when the mainspring is unwound to a number of windings that is equal to or less than a predetermined number of windings, and the unwinding lock mechanism locks the wheel train in order to stop the rotation of the wheel train.
In the present invention, the unwinding of the mainspring can be locked when it is unwound to a predetermined number of windings, so that when the output torque of the mainspring is reduced to a low value and precise hand movements cannot be achieved, the wheel train, that is the hand, can be forced to stop, whereby a torque whose value lies within a set range can be output at all times.
Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.